Researchers Developed a Shape That Might Be the Holy Grail of Soundproofing

Lay down your earplugs and noise-canceling headphones

By Alex Lauer

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11 March 2019

When trying to block an annoying noise, the solution has always been intuitive: put something solid between you and the source of the sound. Loud coworker? Shut your office door. Dog barking while you’re trying to sleep? Slap a pillow over your head. Sure, noise-canceling headphones use different technology, but there’s still that solid barrier.

What if we told you the secret to blocking noise wasn’t a barrier at all, but an open ring?

That’s what researchers at Boston University are claiming with a new study, in which professor Xin Zhang and Ph.D. student Reza Ghaffarivardavagh created an "acoustic metamaterial" that doesn’t block sound, per se, instead it “sends incoming sounds back to where they came from.”

In the video below which demonstrates this technique, “an open, ringlike structure, created to mathematically perfect specifications” is fitted to one end of a hollow PVC pipe. The other end is sealed to a loudspeaker. There’s still an open hole, so you’d expect the sound to pass through just as easily, right? Take a listen:

Yeah, we’ll wait while you play that back a couple more times.

As Fast Companyreports, the potential uses for this technique are endless, from soundproof but transparent walls for cubicles to MRI machines to drones (as only the sound would be negated, not the propeller forces). And the researchers agree, saying they now have the potential to “mathematically design an object that can block the sounds of anything.”